1. Field of the Invention
The invention relates in general to an image forming apparatus and an image transferring method therefor, and more particularly to an image forming apparatus and an image transferring method therefor for color image.
2. Description of the Related Art
Compared with inkjet printers, laser printers provide very high speed and high quality printing of text and graphics. Therefore, laser printers are commonly utilized as computer peripherals for domestic or commercial use to handle the printing of mass documents.
When the laser printer starts its printing process, firstly, the surface of the photosensitive drum or belt inside the laser printer is charged and exposed to form a latent image. After the photosensitive drum (or belt) having the latent image contacts the toner charged by the development system of the laser printer, the toner develops and adheres to the latent image, and therefore transforms the latent image into a toner image. The toner image is then transferred to a sheet. A fuser assembly applies heat and pressure to fuse the toner image onto the sheet. As the printing is completed, residual particles of the toner left on the photosensitive drum will be removed before the next printing starts.
For color laser printer, the toner that consists of toner particles of different colors is needed. Accordingly, the color laser printer employs several photosensitive drums to attract the toner particles of different colors. To transfer the toner particles from different photosensitive drums to the sheet, an intermediate transfer belt (or an intermediate transfer roller) is disposed between the sheet and the photosensitive drums, so that the toner particles are transferred to the intermediate transfer belt (or the intermediate transfer roller) and then to the sheet.
However, after the toner particles are transferred to the surface of the sheet, the toner particles would come off the sheet easily due to the weak Van der Waal's force. The fusing of the toner particles has to be implemented as soon as possible in case that the toner particles come off the sheet and thus the printing quality is reduced.